Improvement in safety-pawls for hoisting apparatus



, R. T. C,RANE & w. H. LAVINIAL Improvement in Safety-Pawls for Ho isting Apparatus.

N0. 128,467. I v 1 Patentedluly 2,1872.

UNITED STATES PATENT OFFICE.

RICHARD T. onANE AND WILLIAM H. LAVINIA, or oHIoAeo, ILLINOIS.

IMPROVEMENT IN SAFETV-PAWLS FOR HOISTING APPARATUS.

Specification forming part of Letters Patent No. 128,467, dated July 2,1872.

We, RICHARD T. CRANE and WILLIAM H. LAVINIA, of Chicago, Illinois, haveinvented certain new and useful Improvements in Safety-Pawls forHoistingApparatus and the following is a full, clear, and exactdescription thereof, reference being had to the accompanying drawing,consisting of one figure, showing an elevation of a portion of theplatformframe and some other parts, with a portion of the frame cutaway. The drawing is on a scale of one and a half inch to the foot.

In the drawing, A B represent part of the frame, to which the platformis connected; O, the cable by which the platform is elevated, and D asafety-cable; E, a bar loose in B, and having shoulders to limit itsmovement. a is a cross-bar or lever, pivoted to E, to which cross-barthe cables are secured. b is a rod, pivoted to a, having an enlargedportion, 0, within which the rod d telescopes, and d is pivoted. to athree-toothed pawl, 0, shown in dotted lines, pivoted at f within theframe, and so formed that the upper tooth will first engage with therack, which is not shown. d is a shoulder on d. g is a springbetween-the shoulder (1 and the end of c,- g, another spring between theshoulder d and the frame. The pawl e is not rigidly pivoted to theframe, but there is a loose bearing, 1', above f. h is arubber springabove the movable bearing i; k, a rod corresponding with b,- and on theother side of the frame are other parts correspondin g with the rods,pawl, and springs above described. Zis another three-toothed pawl,similar to e, pivoted to the frame, having a movable bearing, i, aboveit, and rubber spring h above 6. rack, (not shown.) F is an elbow-lever,pivoted to the frame att; m, a rod pivoted to the pawl Z,- n, a shoulderon m; p, a nut on m. The rod m passes loosely through the end of the arm8 of the lever F. The end of the other arm is pivoted to the lower endof E. r is a spring on m. '0 is a strong spring. On the other side ofthe frame is another pawl, similar to Z, with other parts correspondingwith those last described. I

The upper pawls 6, with the rods and other This pawl also is to engagewith a operating parts, might be used without the pawls l; or the pawlsI can be used without 0; or both can be used together, as represented.

A single cable attached directly to E might be used if only the pawls lare on the apparatus.

In use, if either of the cables should break the bar a will assume aperpendicular position, and the pawl e willbe thrown out by the rods bd, and its upper tooth will engage with the rack. The spring y willyield sufliciently to prevent any imdue pressure upon the rods (1sliding within 0. At the same time the spring y will be compressedbetween the shoulder d and the frame, and at the proper time willwithdraw the pawl e-that is, when the broken cable is restored. While aisassuming a perpendicular position the spring 1;, which is connectedwith the bar E, will force this bar down, and the pawl I will at onceengage with the rack, which is not shown. If only the pawl I be usedwith its operating parts, the cable being connected directly to E, theoperation will be as last described whenever the cable breaks. After thepawl Z has been engaged with the rack, the platform being at rest, whenthe power is again applied to raise the platform, the effect will be tofirst compress the spring 9, and as soon as the pawl is released it willbe withdrawn in .part by the action of the spring 1'. stantially thesame manner.

The spring 9 is much stronger than 9.

The spring h receives the shock caused by the sudden contact of thepawls with the rack in case of accident, which, when the platform isweighted, is severe.

The bar or lever a is not pivoted at its center to E; but the arm towhich the cable 0 is attached is considerably shorter than the otherarm, to which the safety-cable D is connected. These cables are to be soadjusted that when in use the lever a will stand at right angles with E,and, one arm of a being longer than the other, there will be much lessstrain upon D than on 0, so that D will be more surely a safety-cablethan if the .strain upon it were equal to that on G.

What we claim as new is as follows:

The springs g and r operate in sub-- 1. The spring h, in combinationwith the pawl e and movable bearing i, substantially as and for thepurpose specified.

2. The pawl e and spring h, in combination with the bar E, lever a,r'ods b d, and springs g g, substantially as and for the purposesspecified.

3. The pawl l and spring h, in combination with the bar E, spring 1),lever F, rod m, and spring 1", substantially as and for the purposes setforth.

Witnesses:

E. A. WEST, 0. WV. BOND,

